1. Field of the Invention
The present invention relates to a lighting unit for a vehicle using a projector lamp. In particular, the present invention relates to a lighting unit for a vehicle using a projector lamp that increases the visibility while not increasing the size of light source.
2. Description of Background Art
A projector lamp that irradiates light from a light source after concentrating the light source using a convex lens is known. However, a projector lamp according to the background art has a small light emitting surface area and reflection surface for intensifying the light. This means that a light guiding member for improving visibility must be attached (see Japanese Patent Laid open No. 2003-338210).
Also, in the background art, some of the light of the projector lamp escapes to the rear. The light emitting surface area is increased by reflecting this escaped light forwards using a reflector arranged behind the projector lamp (see Japanese Patent Laid open No. 2003-288805).
With any of the above-described examples according to the background art, the light emitting surface area is enlarged from a projector lamp towards its periphery. However, the effect of this on improved visibility is only proportional to the light emitting surface area. In addition, by simply increasing the light emitting surface area, the light amount of peripheral edge sections gradually decreases and visibility is reduced. Therefore, there are evidently limitations in trying to improve visibility simply by enlarging the light emitting surface area.